Android 相机预览显示绿屏

Question

我已经在 Android >= 4.1.2 上实现了相机预览。在 Galaxy S4（两个不同设备）上的 Android 5 上，视图显示三个相机预览和绿屏：

在 Galaxy S3 (Android 4.3)、Galaxy S2 (Android 4.1.2) 和 Galaxy Tab S (Android 5.0.1) 上，它可以正常工作。

这是我的代码如下：

import android.content.Context;
import android.hardware.Camera;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import java.util.List;

@SuppressWarnings("deprecation")
public class CameraView extends SurfaceView {

    private boolean inPreview = false;
    private boolean surfaceCreated = false;

    private Camera camera = null;

    private Camera.Size previewSize = null;

    public CameraView(Context context) {
        super(context);
        SurfaceHolder surfaceHolder = getHolder();
        SurfaceHolder.Callback surfaceHolderCallback = new SurfaceHolder.Callback() {

            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                surfaceCreated = true;
                try {
                    camera = Camera.open();
                    camera.setPreviewDisplay(holder);
                } catch (Exception e) {
                    e.printStackTrace();
                    camera.release();
                    camera = null;
                }
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                if (holder.getSurface() == null || camera == null) {
                    return;
                }
                camera.stopPreview();
                List<Camera.Size> sizes = camera.getParameters().getSupportedPictureSizes();
                previewSize = getOptimalPreviewSize(sizes, width, height);
                startPreview();
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                surfaceCreated = false;
                if (camera != null) {
                    camera.stopPreview();
                    camera.release();
                    camera = null;
                }
            }
        };
        surfaceHolder.addCallback(surfaceHolderCallback);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    public void onResume() {
        if(!inPreview && camera != null && surfaceCreated) {
            startPreview();
        }
    }

    public void onPause() {
        if(camera != null) {
            camera.stopPreview();
            inPreview = false;
        }
    }

    private void startPreview() {
        Camera.Parameters parameters = camera.getParameters();
        parameters.setPreviewSize(previewSize.width, previewSize.height);
        camera.setParameters(parameters);
        camera.startPreview();
        inPreview = true;
    }

    private Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.05;
        double targetRatio = (double) w / h;
        if (sizes == null)
            return null;

        Camera.Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        for (Camera.Size size : sizes) {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
                continue;
            if (Math.abs(size.height - h) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - h);
            }
        }

        if (optimalSize == null) {
            minDiff = Double.MAX_VALUE;
            for (Camera.Size size : sizes) {
                if (Math.abs(size.height - h) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - h);
                }
            }
        }
        return optimalSize;
    }
}

用法：

public class MainActivity extends Activity {

    private CameraView cameraView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        cameraView = new CameraView(this);
        ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
        cameraView.setLayoutParams(params);
        setContentView(cameraView);
    }

    @Override
    protected void onResume() {
        super.onResume();
        cameraView.onResume();
    }

    @Override
    protected void onPause() {
        super.onPause();
        cameraView.onPause();
    }
}

我只支持横向模式。